Mystery Rising: Why is T1D Incidence Rising Globally?

Mystery Rising: Why is T1D Incidence Rising Globally? 150 150 Katie Brind'Amour, PhD, MS, CHES

Type 1 diabetes used to be rare. Late 19th-century estimates put its incidence at about 0.004 percent of the world’s population. But by the end of the 20th century, most nations reported a number 350 times that rate. With many countries continuing to experience a steady rise in new cases of up to 4 percent annually, the word “epidemic” has crept into the scientific literature.

“This is indeed an alarming trend because of the impact that type 1 diabetes has on the daily life and the long-term health of those affected,” says Elizabeth Mayer-Davis, PhD, national chair of the SEARCH for Diabetes in Youth Study, a multi-center effort funded by the National Institute of Diabetes and Digestive and Kidney Diseases and the Centers for Disease Control and Prevention. “The trend of increasing incidence is particularly worrisome because we do not know its cause.”

Speculators list theories such as the hygiene hypothesis, intestinal parasite eradication, rotavirus infection, vitamin D deficiency, early introduction of cow’s milk and a combination of such factors as possible causes of the increase. Although they vary widely, most of these hypotheses aim to explain, in part, why the incidence in type 1 diabetes spiked so dramatically in the second half of the 1900s — a period underscored by improved medicine and cleaner surroundings, but also a rise in artificial diets and more time spent indoors.

Although some of these theories offer compelling evidence and strong associations with the increase in type 1 incidence, Dr. Mayer-Davis, who also has served as vice president of health care and education for the American Diabetes Association, suggests it is too early to pinpoint the reason behind the rise.

“Type 1 diabetes is caused by a combination of genetic and environmental or behavioral effects. I would not speculate on the precise cause,” she says. “International studies are ongoing that will be critical in identifying the environmental or behavioral factors that are acting on genetic risk. From those studies, we hope to identify approaches to prevention.”



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About the author

Katherine (Katie) Brind’Amour is a freelance medical and health science writer based in Pennsylvania. She has written about nearly every therapeutic area for patients, doctors and the general public. Dr. Brind’Amour specializes in health literacy and patient education. She completed her BS and MS degrees in Biology at Arizona State University and her PhD in Health Services Management and Policy at The Ohio State University. She is a Certified Health Education Specialist and is interested in health promotion via health programs and the communication of medical information.